Capacitors are devices able to store electricity. When a voltage is applied to two opposing electrodes of a capacitor, the respective electrodes of the capacitor are charged with electricity. When a direct current (DC) voltage is applied to the electrodes of the capacitor, DC current flows into the capacitor while electricity is stored therein. However, when electricity storage is completed, the DC current no longer flows thereinto. In contrast, when an alternating current (AC) voltage is applied to the electrodes, AC current continues to flow into the capacitor while the polarities of the electrodes alternate with each other.
According to types of insulators provided between the electrodes, such capacitors may be divided into various types: an aluminum electrolytic capacitor having electrodes formed of aluminum and having a thin oxide layer between the electrodes; a tantalum capacitor using tantalum as an electrode material; a ceramic capacitor using a high-k dielectric, such as titanium barium, between electrodes; a multilayer ceramic capacitor (MLCC) provided as a dielectric between electrodes using a high-k-based ceramic as a multilayer structure; and a film capacitor using a polystyrene film provided as a dielectric between electrodes.
Among these capacitors, the MLCC may have excellent temperature and frequency characteristics and may be implemented to have a compact size to thus be applied for use in various fields, such as high-frequency circuits.
MLCCs, according to the related art, have a laminate formed by stacking a plurality of dielectric sheets, external electrodes formed on external surfaces of the laminate to have different polarities, and internal electrodes alternately stacked inside the laminate to be electrically connected to the external electrodes, respectively.
In recent years, with electronic products being formed to have a compact size and high integration, a lot of research into the implementation of compact size and high integration in MLCCs has been conducted. In particular, in the case of MLCCs, various attempts have been made to improve the connectivity of internal electrodes while thinning and highly stacking dielectric layers, in order to achieve high capacity and compact size in MLCCs.
Especially, it has become more important to ensure the reliability of products in which thin-film dielectric layers and internal electrodes are highly stacked. As the stacking number of dielectric layers and internal electrodes is increased, there may be an increase in an amount of step portions formed due to a difference in thicknesses between one portion, such as a central portion of the MLCC, in which the internal electrodes and the dielectric layers are stacked, and another portion, such as an edge portion (or margin portion), in which some of the internal electrodes formed in the one portion may not be formed. Such step portions may cause the end portions of internal electrodes to be bent, owing to the transverse elongation of dielectric layers, in a densification process of pressing MLCC bodies.
That is, the end portions of internal electrodes may be curved when some portions of the dielectric layers reposition to fill the step portions, and margin portions may remove empty space, formed by the step portion, by the depression of covers and a reduction in the margin width. Capacity layers may also be elongated by the margin width reduced by removing the empty space in the margin. Such structurally irregular elongation of internal electrodes may reduce the characteristics of MLCCs, such as breakdown voltage (BDV) characteristics.
The occurrence of the step portion, as described above, may be a problem both in a first direction, perpendicular to the stacking direction of the internal electrodes and the dielectric layers of the MLCCs, and in a second direction, perpendicular to the first direction and perpendicular to the stacking direction. Thus, a need exists for a solution to solve this problem.